Muffler with perforated cylinder containing inwardly and rearwardly inclined holes



W. H. ENGELS MUFFLER WITH PERFORATED CYLINDER CONTAINING Jan. 22, 1952 INWARDLY AND REARWARDLY INCLINED HOLES Filed Feb. 9, 1948 Patented Jan. 22, 1952 MUFFLER WITH PERFORATED CYLINDER .CONTAINING INWARDLY AND REAR- WARDLY INCLINED HOLES Willard H. Engels, Kansas City, Mo.

Application February 9, 1948, Serial No. 7,079

1 Claim.

This invention relates to improvements in mufels for internal combustion engines, and has particular reference to means for muflling expanding and noise producing gases discharged from automobile engines.

The principal object of the present invention is to` provide a device structurally characterized by a novel arrangement of elements functionally related to muilie the noise of exhaust gases discharged from an engine while reducing back pressure upon the gases to a minimum to increase the elciency of the engine.

The explosion of the fuel within an internal combustion engine creates a high pressure therein. Upon the opening of the exhaust ports the gas emerges at high velocity. The result is a succession of pulsations or slugs of gas at high pressure traveling through the exhaust manifold at a high velocity. Upon the release of the gas slug into the atmosphere, another spurt in velocity is acquired due to expansion and a sharp sound results. In order to silence the pulsating exhaust noises the mufiler must suppress the pressure peaks and thus even the ow of the escaping gas pulsations to the point Where the sound generated is substantially uniform at all times.

The present invention presents a structure which smoothes out to a large degree the pulsating eifect of successive exhaust discharges from the engine, without setting up any material back pressure within the engine.

Other objects are simplicity and economy of construction, emciency of operation and adaptability for use with the various types of gas engines.

With these objects in view as well as other objects which will appear during the course of th specication, reference will be made to the drawings wherein:

Fig. 1 is an elevational view partly broken to disclose more fully the features of my invention.

Fig. 2 is a transverse sectional view taken on line II-II of Fig. 1.

Fig. 3 is an enlarged fragmental sectional view portion of the muiiler.

Throughout the several views of the drawings like reference numbers refer to similar parts and the numeral l designates a foraminous cylinder or tube made of a rigid material such as sheet metal provided with a substantially unobstructed central duct l2 through the full length ofthe muliler. The end portions I4 of cylinder l0 are plain and fit respectively into the engine exhaust pipe I6 and outlet exhaust pipe I8, through which the gases are discharged into the atmosphere.

Built about the foraminous portion of cylinder l0 is a housing 20 comprising a tubular wall 22 provided with end plates 24 and 26 whereby a chamber 28 is formed about the said cylinder. As shown wall 22 is concentric with cylinder l0, however, the shape and relationshipv of these parts might be varied if it is found convenient or beneficial. The chamber is provided adjacent the periphery of cylinder l0 with a plurality of convolutions of screen wire 30 which are slightly separated from the cylinder I0 by means hereinafter referred to. Positioned in chamber 28 outside screen wire 30 is packed with a porous, gas pressure absorbing and sound absorbing material, such as mineral fiber, steel, copper or other metallic wool 32 or any other gas pressure absorbing and sound absorbing material that is a non-inammable material, such as expanded vermiculite, porous aggregate, etc. In mounting housing 20 on cylinder I0, it is found convenient to weld the ilange 34 of said plate 24 to the cylinder I0, while the other end plate 26 is provided with an inwardly turned flange 36 and an outwardly turned flange 38, to present a sliding fit for the cylinder i 0. By means of this form of mounting, unequal expansion of parts will be compensated for to prevent separating of the joints.

Referring now specifically to Fig. 3 it will be noted that the foraminations or openings 40 are formed through cylinder i0 at an acute angle to the axis of the cylinder and in the general direction of the flow of gases therethrough, as indicated by the arrow. The flange or lip 42 at the forward edge of hole 40 is inclined inwardly in the general direction of flow of gases in cylinder I0. The ilange 44 at the rear edge of hole 40 is inclined outwardly against the direction of exhaust gas iiow through cylinder i0. As the highly pulsating gas discharges pass through cylinder I0 each pulsation or slug of gas in passing lip 42 will create a suction to pull gases from 28, then as the low pressure phase of the gas flow through cylinder I0 registers with said hole I0 gas will be drawn into chamber 28 thus tending to smooth out the gas flow. After this process has been repeated many times due to the presence of the many holes, as shown, the pulsating gas flow will be gradually smoothed out and the noise will be reduced to a uniform minimum, which will present a substantially constant uniform hum, which is not objectionable to the ear.

It will be noted that openings 40 in general pattern are arranged in spiral rows to spin the gases and thereby to further lend to the smoothing of the pulsating gas stream by suppressing the pressure peaks, and also to the silencing of the noise created by the escaping gas. The lips 44 extending outwardly from the cylinder l0 serve also as bearing points for screen 30 thus holding the screen in slightly spaced relation to the outer periphery of the cylinder I0.

From the foregoing description it is evident that I have produced a simple and comparativea ly inexpensive muler which effectively smoothes out the pulsating gases discharged from an internal combustion engine and mufes the attendant noises, and at the same time reducing the back pressure to a minimum.

What I claim is:

A muler comprising a perforated cylinder having a substantially uniform gas duct extending therethrough, a closed casing formed about saidv perforated cylinder to form a chamber thereabout, a layer of screen positioned in said chamber about said perforated cylinder, a sound absorbing material filling said chamber between said screen and said casing, said perforated cylinder being formed to present inwardly and rearwardly inclined lips at the forward edges of the perforations therein and outwardly and forward- 4 ly inclined lips at the rearward edges of said perforations, said outwardly inclined lips contacting and supporting said screen in spaced relation from said cylinder.

WILLARD H. ENGELS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,811,762 Schnell June 23, 1931 1,927,213 MacKenzie Sept. 19, 1933 2,065,343 MOOre Dec. 22, 1936 2,073,951 Servais Mar. 16, 1937 2,233,804 Bourne Mar. 4, 1941 2,241,150 Miller May 6, 1941 FOREIGN PATENTS Number Country Date 379,563 Great Britain Sept. 1, 1932 561,675 Germany Oct. 17, 1932 782,848 France June 12, 1935 461,065 Great Britain Feb. 9, 1937 469,155 Great Britain July 20, 1937 512,075 Great Britain Aug. 29, 1939 

